Alumina ceramic plunger, alumina ceramic piston, alumina ceramic cylinder Alumina content: 97%, 99% Density: 3.75g/cm3, 3.84g/cm3 Hardness: 85Hra, 88Hra(Rockwell) Surface roughness: Ra0.2-0.3um(polished) Ra0.6-0.8um(unpolished) Dimension: as per request Dimension tolerance: as per request It is mainly used in high pressure pumps or cleaners.